How to measure consciousness

GIULIO TONONI'S charming book Phi is an account of consciousness that nods in its style to the writings of a fellow Italian. Yet while Dante had the poet Virgil to guide him on his journey through the circles of hell in the Divine Comedy, Tononi's elderly traveller Galileo draws on the expertise of three great scientific minds. Journeying into the nature of consciousness he is led by a Francis-Crick-like character, someone who must be Alan Turing and finally Charles Darwin.

Is Tononi trying to tell us that the vast philosophical morass of consciousness - what it is, where it resides, how it arises from a purely physical brain - is a kind of hell? And, like hell, is the scientific and philosophical study of consciousness a place from which few ever return?

In spite of having acquired a vastly improved understanding of the physical, chemical and neuronal structures of the brain, we seem little advanced over the ancient Greeks in our subjective understanding of this mysterious feature of our existence.

It is still the case, for example, that each of us knows we have consciousness but can't be sure anyone or anything else does. Mindful of this, Tononi, a neuroscientist at the University of Wisconsin-Madison, avoids the usual traps and lays out a computational theory that describes consciousness as arising from "integrated information", a quantity he denotes with the Greek character Φ of his title.

Think of it this way: your digital camera has a prodigious memory capacity but its millions of pixels never "see" a photo. Your mind can because your brain actively constructs scenarios, tableaux and even simple perceptions from the integrated inputs of myriad specialised circuits. So Φ is a measure of that integration.

Tononi's approach can explain some curious phenomenology of consciousness. Why do we lose consciousness when we go to sleep? He would say that this is a time when information from the brain's specialised circuits is no longer integrated. Why are brain seizures associated with a loss of consciousness? Again, seizures seem to block complex informational exchange.

These ideas move us closer to grasping what consciousness is because, if Tononi is right, he can in principle measure varying degrees of consciousness among different people, or even different organisms. But what about bats - those famous subjects of debates on consciousness? Are we any closer to knowing what it is like to be one? Not yet, it seems, but perhaps now Tononi at least has students of consciousness travelling along the path to Paradise.

Mark Pagel is an evolutionary biologist at the University of Reading, UK. His latest book is Wired for Culture (Allen Lane/W. W. Norton)

Surveying North America's Arctic shores

Erin Wayman, contributor

BETWEEN 1492 and 1542, European explorers mapped the coastlines of
South America, Central America, and much of the east and west coasts of North America. Yet it took a further 350 years of navigating treacherous Arctic waterways to finish the outline of the New World. Even then, the North-West Passage remained elusive. The triumphs and failures of the centuries-long struggle to survey those Arctic shores are the main focus of geographer Roger McCoy's On the Edge.

Back then, the far north was even more frigid than today. The Little Ice Age,
which began in the 1300s and lasted for 400 years, made the climate harsh and unpredictable: extensive sea ice meant the region was navigable for only a few months of the year, and channels open one summer might be frozen shut the next.

By the 19th century, the British -the main mappers of the Arctic - still hadn't found a sea
route connecting the Atlantic and Pacific. But pride prevented them from giving up. Fortunately, expeditions started to collect data about polar geology, climate and natural history. Those records are now an important benchmark for researchers investigating climate change, McCoy explains.

Yet some of the significance of these journeys is lost in what often feels like an endless list of expeditions that follow the same script: a captain sets sail confident, his ship gets stuck in ice, sailors sit around a lot, problems arise, men starve and the expedition is saved (or not).

The repetition highlights
the real failure of the Arctic explorers - their inability, or refusal, to learn survival tactics from the local people. And sadly it also highlights McCoy's missed opportunity to breathe more life into an important era of our geographical history.

1 Comment

Tononi's measure consciousness is based on the underlying assumption that Phi is a continuum. There is no Rubicon that separates a conscious entity from a non-conscious one, thus organisms have differing degrees of consciousness. I would suggest that all the higher animals are conscious to one degree or another with mammals and birds having levels of consciousness similar to our own. I think humans know this intuitively but deny it so they can distance ourselves from its implications which are quite profound and would necessitate a complete change in our treatment of other conscious beings.